Sharon Rugel Long (born March 2, 1951) is an American plant biologist. She is the Steere-Pfizer Professor of Biological Science in the Department of Biology at Stanford University, and the Principal Investigator of the Long Laboratory at Stanford. Long studies the symbiosis between bacteria and plants, in particular the relationship of nitrogen-fixing bacteria to legumes. Her work has applications for energy conservation and sustainable agriculture.She is a 1992 MacArthur Fellows Program recipient, and became a Member of the National Academy of Sciences in 1993.